Machine for grinding gear teeth by the generating process



July Q 1940. F. LINSEZ El" AL 2,207,013

MACHINE FOR GRINDING GEAR TEETH BY THE GENERATING PROCESS FiledAug. 20, 1937 5 Sheets-Sheet l I Zwenlan F7772 .Z/msc J/fameya July 9, 1940. msE' r AL I 2,207,018

MACHINE FQR GRINDING GEAR 'IGLE'IYIIBY THE GENERATING PROCESS Filed Aug. 20, 1937 s Sheets-Sheet 2 EM Affv/wey y 9, 1940- F. LINSE gr AL 2,207,018

MACHINE FOR GRINDING GEAR TEETH BY THE GENERATING PRQCESS Filed Aug. 20, 1957 5 Sheets-Sheet 3 M Java/way: Y.

ATING PROCESS 5 Sheets-Sheet 4 July 9, 9 F. LINSE El AL MACHINE FOR GRINDING GEAR TEETH BY THE GENER Filed Aug. 20, 1937 July 9, 1940. 4 5; AL 2,207,018

MACHINE FOR GRINDING GEAR TEETH BY THE GENERATING PROCESS Filed Aug. 20, 1937 5 Sheets-Sheet 5 Zwcnion v279/7 .Z/mae,

Patented July '9, 1940 UNITED S ATES momma FOR enmnme GEAR. TEETH BY THE GENERATING. moorss Fritz Linse, Chemnitz, Saxony, and Albert Bellmann, Glauchau, Saxony, Germany Application August 20, 1937, Serial No. 160,188

In Germany September 25, 1936 10 Claims.

The invention relates to machines for grinding gear teeth by the generating process by means of two flat grinding wheels which are inclined at the flank angle to one another. In the known machines of this kind, the two grinding wheels have been arranged so that their axes were disposed in the same plane perpendicular to the axis of the blank. The wheels have therefore been positioned with their backs inclined at the flank angle and opposite each other. Any other arrangement has been impossible, since the axes of the grinding wheels lay in the same plane. Even if it has been" advantageous for both wheels to work simultaneously, the known wheel arrangement was accompanied by a large number of considerable disadvantages. In the first place, in consequence of the lack of space, it has only been possible to make the grinding wheels and also their mounting, grinding wheel spindles and the means of attachment of the grinding wheels to the spindles, of a weak con-'- struction. Consequently, it has only been possible to grind ofi relatively thin chippings with a slight feed. The mounting and the spindles have consequently had to be weak because they could only be arranged onthe side of the flat grinding surfaces, the consequence of which has again been that they projected into the rolling space of the blank. If the size of the blank was not to be limited excessively, it has only been possible to attain this at the expense of the mounting and the thickness of the spindles.

Truing of the grinding wheels has only been possible in the work pauses, and has had to be avoided as far as possible inprder not to increase the machining time quently, the width of the flat annular grinding surfaces has only been made small (2 mm.) since it is knownthat such narrow grinding edges are 40 self-truing. This slight width of the grinding edge in its turn implies a small feed and therefore reduces the output of the machine.

The grinding wheels being situated in the same plane perpendicular to the axis, it has only been possible in the case of coarse pitches to incline them in such a manner that two wheels could be inserted in the same tooth gap. The smaller the pitch, the more gaps and teeth have had to be situated between the simultaneously machined tooth flanks. For example, in the case of the module 2 to 2.35, two teeth and three tooth gaps lie between the machined flanks, and in the case of module 3.5 to 7.5 one tooth and two gaps. Only fromthe module 8 onwards, has it been 5 possible to insert 'both grinding wheels in the same gap. Thus, the rolling movementhas risen to 7 pitches for module 2.

Due to the weakness of the grinding wheels, the weakness of their mounting, of their spindles 6 and their means of attachment to the spindles,

unnecessarily. Consethe diificulty of truing and the necessity for a, narrow grinding edge, as well as the considerable generating or rolling movement, the output or the known machines has been extremely reduced. An increase in the output would only have been 5 possible by overstraining the machine and hence at the expense of the quality of the grinding obtained.

All these disadvantages are obviated by the grinding machines of the invention, which is characterised in that the two grinding wheels are offset relatively to one another in the longitudinal direction of the tooth flanks so that the grinding wheels do not overlap'one another. With this arrangement of the grinding wheels, it is possible to take a single tooth between the flat grinding surfaces or to insert both grinding wheels in the same tooth gap, since the wheels may now be inclined so that the planes of their grinding surfaces intersect, this arrangement being possible from module 2 upwards to the coarsest of pitches.

Consequently, a further feature of the machine according to the invention is that the grinding wheels grind both flanks of the same tooth or the same gap. Furthermore, according to the 5 invention, the grinding spindles may be situated on the grinding wheel backs opposite the fla grinding surfaces.

It follows therefrom that for all occurring teeth, the rolling angle may be reduced to a minimum. Furthermore, the grinding spindles and hence also their mounting and their drives may be situated entirely outside the space necessary for the rolling of the blank, and in fact so high above the imaginary rack for the generation that spindles and mountings may be constructed in a practically rigid manner. Likewise-the limitation regarding the strength of the grinding wheels and the fixing of the wheels on their spindles is eliminated, since the wheels no longer lie opposite each other. In consequence of the strong construction of the wheels, of their flx- .ing means and their mounting, it is possible to. work with a thick chipping and considerable feed without endangering the quality of the work. The considerable feed shortens the time of the grinding work-for each-stroke and the considerable thickness of chippings reduces the number of grinding strokes. r

In the grinding wheel arrangement according to the invention, the in-feed and truing device of each grinding wheel may be set in operation during the idle running of' the wheel. Truing may therefore be carried out as often as desired without loss of time, so that it is possible to dispense with the narrow self-truing grinding edge. The width of the grinding edge on the contrary may be selected in accordance with the feed or vice versa. The possibility of using wide grinding edges likewise permits of a considerablefeed. 5o

The advantages depicted are so considerable that the apparent disadvantage that the two oflset wheels operate successively, so that a larger grinding stroke of the wheels relatively to the blank is necessary, is not only outweighed but a machine according to the invention requires a quence of the greater possible thickness of chippings, the number of grinding strokes may be reduced. The capacity of the machine is on the whole at least doubled.

Machines are also known in which grinding wheels having a conical grinding surface are employed. The machine according to the invention, like any machine with fiat grinding surfaces, is superior to said known machines in that more accurate grinding is secured (continuously curved tooth profile instead of facet grinding).

A construction of a grinding machine according to the invention is shown by way of example in the accompanying drawings.

Figure 1 is a side view of the grinding machine.

Figure 2 is an end view of the machine seen from the indexing head side, with the rolling arc housing removed.

Figure 2a is a view of the rolling arc housing.

Figure 3 is an end view of the machine from the driving side.

Figure 4 is a plan of the machine partly in horizontal section half way up the machine.

Figure 5 is a gear diagram of the bevel wheel drive in the oscillating bed of the machine.

Figure 5a is a plan of Figure 5 seen in the direction of the arrow.

Figure 6 shows the grinding wheels in engagement with the blank.

Figure '7 shows diagrammatically the grinding wheels and rack and the development of a wheel therein.

Figure 8 shows diagrammatically the passage of the grinding wheels through the blank.

Figure 8a. shows diagrammatically the distance which, is bridged over by the quick-motion.

Figure 9 shows diagrammatically the drive of the grinding spindle, the drive of the changespeed gears, and the drive of the in-feed and truing devices.

In the drawings the machine bed is denoted by I, the gear blank by 2 and the grinding wheels by 3 and 4; The gear blank wheel is carried by a mandrel 5 held by the centres 6 and I. The centre 6 is connected with the pitch apparatus 8, which may be of any desired construction. Behind the pitch apparatus 8 and likewise connected to the mandrel 5, is the rolling are 9 which is connected to the pitch apparatus 8 and the blank 2 in any manner which permits these parts to oscillate together without rotating relatively to one another. The division from tooth to tooth is effected independently of the rolling operation. Above the rolling are 9 there are tensioned steeltapes l8 and Il. These steel tapes are secured externally to a frame 12 and are tensioned by means of tensioning devices l3 and l3a, which in their turn are vertically adjustable. With this arrangement, the pivot of the rolling are 9 and of the pitch apparatus 8, the

centres 6 and I and the mandrel 5 move with the gear blank 2 horizontally on a straight line. For taking up the weight of these parts a slide I5 is provided which is transversely movable in a guide I 6 on the machine bed.

The drive of the rolling are 9 is effected by means of a crank disc I! and a crank rod l8 engaging the slide l5 at point I9. The drive of the crank disc will be described hereinafter.

On the bed I is a standard 28 on which is vertically slidable a slide 2| having a horizontal slideway 22 situated in the longitudinal direction of the machine. In the slide way 22 is a slide 23 from which are slidably suspended the bearing brackets 24 and 25. Furthermore the slide 23 carries the housings 26 and 21 for the drive of the grinding wheel in-feed and truing devices and the driving motors 28 and 29 for the grinding wheels 3 and 4 and the in-feed and truing devices.

Rotatably and flxably mounted on the bearing brackets 24 and are the grinding headstocks 30 and 3| with the in-feed and truing devices for the grinding spindles 32 and 33. I

Belt drives 34 and 35 are provided for driving the grindingspindles and the in-fed and truing elements. Connection between the in-feed and truing devices in the headstocks 30 and 3| and the drive housings 26 and 27 is eflected by means of articulated shafts which, however, are not leads upward to a belt pulley on a shaft 4| which extends into the maingear box, in the interior of which are accommodated all the pinion and control elements for the rolling movement, for driving the pitch device, driving the grinding spindle slide and for the feed and quickmotion thereof.

, Above on the main gear box 42 is a longitudinal slide 43 which receives its reciprocatory movement from the main gear box, through a rack 43' mounted on the underside of the slide 43 and meshing with a driving gear 43" in the gear box which in turn is alternately driven in opposite directions from the main shaft 4|, through conventional control and transmission means (not shown), as will be readily understood by those skilled in the art. The movements of this slide are transmitted by a vertical stationary shaft 44 and by wheels 45 and 46 in conjunction with the racks 41 and 48 to the grinding spindle slide 23. Furthermore, mounted on the longitudinal slides 43 are longitudinally slidable stops 49 for conaccording to the invention'serves for the production of spur wheels. For grinding helical wheels, the rolling slide guide l6with the rolling slide l5 and the rolling tape housing I 2 are oscillated about a vertical-axis 50- in accordance with the angle of tooth obliquity of the gear blank to be machined. For this purpose, the'machine bed I carries an arcuate siideway 5| for an oscillating bed 52 carrying the rolling slide |5 and the rolling 5 tape housing l2. In addition, the oscillating bed 52 is provided with a guideway 53 in which the rolling arc housing I2 is slidably. and flxably guided in order to be able to effect an angular adjustment of the gear blank 2 by means of the 10 rolling arc 9 and the rolling tapes l0, ll.

Extending from the main gear box 42 is a shaft 54 which by means of the bevel gear pairs 55 and 56 in combination with a gear train, not shown in the figures, drives the crank disc ll for driving 13 the rolling slide l5.

In shaft 54 there also lies a second shaft and this shaft, by means of the bevel gear pairs 51 and 58 and a further gear train, which is likewise not shown in the figures, serves for driving'the I) pitch apparatus 8. A fuller description of the indexing or pitch operation is again unnecessary in the scope of the application.

It will now be pointed out that in all cases. further indexing from tooth to tooth is eflected 85 by the gear blank after each passage of the grinding wheels in the longitudinal direction of the tooth flanks. u

Figures 6, 7 and 8 serve to explain the theoretical principle of the machine. Figure 6 shows 30 the grinding wheels 3 and 4 in engagement with a tooth of the gear blank 2, the flat plane surfaces 59 and 60 of the grinding wheels representing the tooth gap of a rack. It does not require .any further explanation to see that during the rolling of the blank, the effective surfaces of the grinding wheels must produce involute curves.

Figure '7 shows the flat plane surfaces 59 and 60 of the grinding wheels placed in an imaginary rack GI and the corresponding gear blank 2 in 40 the end positions of the rolling movement. In

. this figure, A is the rolling path which is necessary for rolling a tooth of the gear blank on the grinding surfaces of the tool.

Figure 8 shows the relative positions of the 45' grinding wheels and gear blank during machining. Only one tooth 62 of the gear blank is shown in longitudinal section. The grinding wheels 3 and 4, before each working stroke, are situated either in theposition shown entirely on the right 40 or entirely on the left. Assuming that the wheels start from the right-hand position; then the wheel 3 will first run along one flank of the tooth 32 which is rolling to and fro. Figure 8a shows the position of the grinding wheels 3 and I5 4 relatively to the single tooth 32 after the- Brinding wheel 3 has run completely through the tooth. The approach of the grinding wheel 4 to'the -i;ooth isreflected-hy quicksmotion whereupon the e of the wheel 4 along the other flank of co the same tooth is completed. After the wheel 4 has completely passed through the gear blank, the further indexing movement of the gear by one tooth is eflected and the cycle described iscompleted again in the opposite direction. In Figas are 8, B is the total path which the grinding slide 23 has to make in this case. In Figure 841, C is the path-which is travelled in the quick-motion of the grinding slide. In Figures 8 and 8a,

theconstant grinding wheel distance is D andthe 7 tooth to-be ground is E. It requiresno furtherexplanation to see that an increase of E eifects a reduction in D. As already stated, while one grinding wheel is in' the working position, the

other grinding wheel-maybe automatically trued. 75 and vice versa. 8inee,tberefore, no special working time is employed for truing the grindin wheels, the truing of'the wheels, as already mentioned, may be eflectei as often as desired without loss of time.

A truing device is indicated diagrammatically in ,Figure 6. Mounted on the grinding headstocks 30 and 3| are pins 63 and 64, respectively, carrying the rocking arms 65 and 65, on the free ends whereof are the truing diamonds. These arms, as indicated in Figure 8, having the same 10 spacing as wheels 3 and 4, and are adapted to be swung to and fro automatically over the width b of the edge of the grinding wheels 3 and 4 totrue the wheels on each stroke away from the work gear. Swinging is'efiected in any known manner by means of the control mechanisms accommodated in the grinding headstocks and 3|. The control of the mechanisms is effected by means of adjustable stops 61 on the horizontal slideway 22. As shown in Fig. 1, the stop 61 is 20 pivotally mounted to carry out a switching movement that is transmitted to the driving and control mechanism in the gear box through the rotation of the pivot of the stop. The skilled person has suflicient mechanisms available for this purl6 pose.

Figure 9 shows diagrammatically the combined drive for the grinding spindles and for the infeed and truing devices seen in plan.

We claim: .9

1 In' a machine for grinding gear teeth by the generating method, means for rolling the roughed out blank as on a basic rack, means for reciprocating the grinding wheels longitudinally of the I gear teeth, said reciprocating means comprising a a slideat the top of the machine. above the blank adjustable up and down and movable to and fro longitudinally of the gear teeth, a pair of independently slidable cross slides hanging downward therefrom, grinding wheels having aflat" grinding face carried by said cross slides, the grinding faces of said wheels being at the flank angle of the teeth of said basic rack, said grinding wheels being offset longitudinally of the gear 'teeth tobe displaced in their projections by a substantially constant amount, and means for fieding the grinding wheels in a crosswise direcon.

2. In a machine for grinding the working sur faces of the teeth of gear wheels, a tool unit comprising a pair of grinding wheels each having a planar operative grinding face,means for rotatably supporting said grinding wheels in spaced relationship at a distance between their axes amounting at least to the maximum diameter of one of said grinding wheels, and with the planar grinding faces inclined at the flank angles of two consecutive tooth flanks of a rack mateable with the gear teeth to be.ground,'a work gear holder, 5 means to reciprocate said tool unit relative to said 00 work gear holder to bring said grinding wheels into successive engagement with a gear wheel, and means 'to roll the work gear with its pitch line on the grinding wheels. 3. In a machine for grinding the working sun-'- faces of the teeth of gear wheels, a tool unit comprising a pair of grinding wheels each having a planar operative grindingface, means for rotatabiy supporting said grinding wheelsin spaced relationship with a distance between their axes which is substantially constant during operation andamounts at least to' the maximum diameter of one of said grinding wheels, andwith their planar grinding faces inclined at the flank angles.

of two consecutive tooth flanks of a rack mateable "l5 with the gear teeth to be ground with the angle between the grinding wheel axes directed with its vertex towards the work gear, a work gear holder, means to reciprocate said tool unit relative to said work gear holderto bring said grinding wheels into successive engagement with a gear wheel, and means to roll the work gear with its pitch line on the grinding wheels.

4. In a machine for grinding the working surfaces of the teeth of gear wheels, a tool unit comprising a pair of grinding wheels each having a planar operative grinding face of considerable radial extension, means for rotatably supporting said grinding wheels in spaced relationship at a distance between their axes which is substantially constant during operation and amounts at least to the maixum .diameter of one of said grinding wheels, and with their planar grinding faces inclined at the flank angles of two consecutive tooth flanks of a rack mateable with the gear teeth to be ground, a work gear holder, means to reciprocate said tool unit relative to said work gear holder to bring said grinding wheels into successive engagement with a gear wheel, and means to roll the work gear with its pitch line on said grinding wheels.

5. In a machine for grinding the working sur faces of the teeth of gear wheels, a tool unit comprising a pair of grinding .wheels each having a planar operative grinding face, means for rotatably supporting said grinding wheels in spaced relationship with a distance between their axes of not less than the maximum diameter of one of said 'grinding wheels, and with their planar grinding faces inclined at the flank angles of the two flanks of a tooth of a rack mateable with the gear teeth to be ground, a work gear holder, means to reciprocate said tool unit relative to said work gear holder to bring said grinding wheels into successive engagement with a gear wheel, and means to roll the work gear with its pitch line on said grinding wheels.

6. In a machine for grinding the working surfaces of the teeth of gear wheels, a tool unit comprising a pair of grinding wheels each havinga planar operative grinding. face, a spindle extending fromeach grinding wheel from the side opposite said operative face, means for rotatably supporting said spindles in spaced relationship with a distance between their axes which is substantially constant during operation and amounts at least to the maximum diameter of one of said grinding wheels, and with the planar grinding faces inclined at the flank angles of two consecutive tooth flanks of a rack mateable with the gear teeth to be ground, a work gear holder, means to reciprocate said tool unit relative to said work gear holder to bring said grinding wheels into successive engagement with a gear wheel, and' means to roll the work gear with its pitch line on said grinding wheels.

7. In a machine for grinding the working sur- I faces of the teeth of gear wheels, a tool unit comprising a pair of grinding wheels each having a planar operative grinding face, means for rotatably supporting said grinding wheels in spaced relationship with a distance between their axes which is substantially constant during operation and amounts at least to the maximum diameter of one of said grinding wheels, and with their planar grinding faces inclined at the flank angles of two consecutive tooth flanks of a rack mateable with the ear teeth to be ground, a work gear holder, in ans to reciprocate said tool unitrelative to said work gear holder to bring said grinding wheels into successive engagement with a gear wheel, by strokes causing successive engagement of the -two grinding wheels with the work gear, and means to roll the work gear with its pitch lineon said grinding wheels.

8. In a machine for grinding the working surfaces of the teeth of gear wheels, a tool unit comprising a pair of grinding wheels each having a planar operative grinding face, means for rotatably supporting said grinding wheels in spaced relationship with a distance between their axes which is substantially constant during operation and amounts at least to the maximum diameter ing wheels into successive engagement with a gear wheel, means to roll the work gear with its pitch line on said grinding wheels, and means for truing the grinding wheels positioned for the truing operation upon non-engagement of the respective grinding wheel with the work gear.

9. In a machine for grinding the working surfaces of the teeth of gear wheels, a tool unitgcomprising vertically adjustable slide means, a pair of grinding wheels each having a planar operative grinding face, means for rotatably supporting said grinding wheels in depending adjustable position upon said slide means in spaced relationship with a distance between their axes which is substantially constant during operation and amounts at least to the maximum diameter of one of said grinding wheels, and with their planar grinding faces inclined at the flank angles of two consecutive tooth flanks of a rack mateable with the gear teeth to be ground, a work gear holder, means to reciprocate said tool unit relative to said work gear holder to bring said grind ing wheels into successive engagement with a gear wheel, and means to roll the work gear with its pitch line on said grinding wheels.

' 10. In a machine for grinding the'working surfaces of the teeth of gear wheels, a machine frame, a tool unit comprising vertically adjustable slide means, a pair of grinding wheels each having a planar operative grinding face, means for rotatably supporting said grinding wheels in depending adjustable position upon said slide means in spaced relationship with a distance between their axes which is substantially constant during operation and amounts at least to the maximum diameter of one of said grinding wheels, and with their planar grinding faces inclined at the flank angles of two consecutive tooth flanks of a rack mateable with the gear teeth to be ground, a-work gear holder, means to reciprocate said tool unit relative tosaid-work gear holder to bring said grinding wheels into successive engagement with a gear wheel, a second 

